High-Frequency Basal Cell Carcinoma: Demographic, Clinical, and Histopathological Features in a Belgian Cohort.

Background: Basal cell carcinoma (BCC) is the most common skin cancer worldwide, with a multifactorial aetiology involving environmental and intrinsic factors. A small subset of patients develops high-frequency BCC (HF-BCC), defined as ≥9 BCCs within 3 years. Objective: To analyse demographic, clinical, and histopathological features of non-syndromic HF-BCC in a Belgian cohort, compared with low-burden BCC patients and healthy controls. Methods: A retrospective cohort study was conducted at Erasme Hospital (Brussels) using data from the EUSCAP platform. Clinical, behavioural, and histopathological data were collected and statistically analysed. Results: Of 783 patients, 16 with HF-BCC were identified. For comparison, 32 patients with 1-2 BCCs and 117 patients without BCC were selected. HF-BCC patients showed distinct characteristics, including a higher proportion of superficial BCCs (68.3% vs. 50%, p = 0.01) and fewer nodular subtypes (43.2% vs. 63.5%, p = 0.01). Their tumours were less frequently located on the nose and ears compared with patients having 1-2 BCCs. HF-BCC was associated with a personal history of squamous cell carcinoma (SCC) and actinic keratosis (AK). Conclusions: HF-BCC patients display distinct anatomical, histopathological and clinical characteristics, with a predominance of superficial BCC and an association with a personal history of SCC and AK. They show a lower frequency of tumours on the nose and ears, with a stronger tendency for localisation on the trunk and extremities. Identifying risk factors and genetic markers may contribute to improved early detection strategies, preventive measures, and the development of targeted therapies.